Electricity (FOR SIMPLEPLANES)
Ok, I really want an electric engine, and other electric equipment peices, then ways to supply electricity, including but not limited to, batteries. Ion tanks. Solar panels. Turbines (no I don't mean big tall towers, I mean just the propellor bit, you can have some propellors feeding energy to motor propellors, brilliant when you've started moving).
More building parts, more engine choices, Weapon systems, and add an engine powered by electricity